Doug,
I was impressed by the Dew-diligence of your answer and agree with most of
it.
IMHO the design of the electronics should stand on it's own merits.The use
of coatings allows the use and performance in harsh environments,without
having to derate them.This makes it imperative to now the operating
conditions, possible environmental exposures and the end user applications,
before choosing the coating or application method.
Dewey

> -----Original Message-----
> From: Douglas O. Pauls [SMTP:[log in to unmask]]
> Sent: Wednesday, March 10, 2004 6:33 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Pros and Cons on Type UR vice Type AR Conformal
> Coating
>
> Graham Naisbitt wisely opines:
>
> I was once asked: "does you coating survive exposure to "Skydrol", an
> aviation hydraulic fluid that should NEVER be drunk!!! (Worse than
> Mountain
> Dew I am told!)
>
> **True.  One of the few things more harmful than Mountain Dew.  It is a
> very corrosive and goes through acrylic coatings like a hot knife through
> butter. It's almost impossible to clean thoroughly from a board without
> destroying the assembly.
>
> I asked why, and was informed that it was: "in case the circuit gets
> sprayed
> by this stuff whilst in flight."
>
> My reaction: "This is a circuit in the cockpit of the aircraft, and you
> are
> worried about the effects of a hydraulic leak of Skydrol spraying onto a
> circuit in a sealed housing - why? There ain't no pilot still in
> there...."
>
> **I bet the housing was not truly sealed.  In addition, avionics are
> sprinkeled all throughout the plane and not just in the cockpit.  Avionics
> bays are often co-mingled with hydraulic lines.  Avionics are in the wings
> with the fuel tanks.  Under the toilets.  Most aircraft manufacturers and
> the FAA want you to show that your coating will survive common aircraft
> fluids.  Knowledge of your end-use environment and possible contaminants
> is
> critical in a choice of coatings.
>
> Doug Pauls
>
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